The purpose of this project is to determine the causes of diabetic retinopathy and ultimately the optimal methods to prevent it. All participants in the Pima Indian Longitudinal Study of Diabetes are invited to have their retinas digitally photographed. Batches of photographs are periodically sent for systematic reading for research purposes. The results of these systematic readings become the outcomes for analyses of predictors of diabetic retinopathy. Analysis of data from this project has recently suggested that an area on chromosome 1 may harbor a gene or genes conferring susceptibility to diabetic retinopathy.